Who could be the main antagonist in a 'Criminal Luke Skywalker' fanfic?

A new alien race with a natural inclination towards the dark side could be the main antagonist. They see the Jedi as a threat to their way of life, which is based on conquest and domination. Luke has to figure out a way to either defeat them or find a way to coexist while still upholding the Jedi values.

One possible plot could be that Luke Skywalker turns to the dark side and starts committing crimes against the New Republic in order to gain more power for himself. He might start stealing valuable artifacts or information that could give him an edge. Another plot could be that he is framed for crimes he didn't commit and has to go on the run, trying to clear his name while also being hunted by the authorities. A third plot could involve Luke being under the influence of an evil force or entity that makes him act in a criminal way, and his friends have to find a way to break the influence and save him.

Roman Torchwick would be an obvious choice. He already has a criminal background in the RWBY series. He could return with a new and more devious plan, perhaps teaming up with other villains to cause chaos.

It could be a detective who is hell - bent on capturing Ash. This detective might have a personal vendetta or just be really dedicated to bringing criminals to justice.

Darth Vader could be an unexpected ally in a time travel scenario. If Luke travels to a time when Vader was still Anakin Skywalker and on the verge of turning to the dark side, Luke could try to prevent his fall. In the process, Anakin might become an ally, using his skills as a powerful Jedi to help Luke in whatever mission he has in that time period.

One great Luke Skywalker fanfic to start with could be 'The Life and Times of Luke Skywalker' as it delves deep into his character, exploring his journey not just as a Jedi but also as a person. It gives a very in - depth look at his relationships, his growth, and his struggles, which is really engaging for any Star Wars fan.

Luke's friends from the light side could also be important. Characters like Leia, Han Solo, or Chewbacca. Their reactions to Luke's turn and their attempts to bring him back would be significant aspects of the story. There could also be new characters created specifically for this novel, perhaps some Jedi who were thought to be dead but are actually in hiding and oppose Luke's new path.

Palpatine could still be the main antagonist even if Luke turns to the dark side. He might try to use Luke as a more powerful weapon against any remaining Jedi or the Rebel Alliance. Palpatine would see Luke's newfound dark side power as a means to further his own control over the galaxy.

It could be the remaining Jedi. Since Luke is turning to the dark side, the Jedi who still uphold the light side values would be against him. They would see him as a threat to the balance they are trying to maintain and would try to stop him from fully embracing the dark side.

It could also be Lila. In this au, she could be a master manipulator who uses her lies to create chaos among the heroes and the citizens. She teams up with other criminals and uses her charm to get away with various crimes while making Ladybug and Chat Noir look bad. She might even be able to get her hands on some sort of powerful weapon or item that gives her an edge over the heroes.